Lens module and image apparatus

Abstract

A lens module for capturing an object light-beam from an object-side is provided. The lens module includes a first lens group, a second lens group, a third lens group, a fourth lens group and a fifth lens group sequentially-arranged from the object-side to an image-side. The five lens groups respectively have at least one lens with positive refractive-power and at least one lens with negative refractive-power. The first, third and fifth lens groups are fixed groups, while the second and fourth lens groups are movable groups. An image apparatus including the lens module is also provided.

What is claimed is: 
     
       1. A lens module, having an object-side and an image-side for capturing an object light-beam from the object-side, the lens module disposed on a transmission path of the object light-beam and comprising five lens groups from the object-side to the image-side:
 a first lens group with positive refractive-power; 
 a second lens group with negative refractive-power; 
 a third lens group with positive refractive-power, wherein the third lens group comprises a first lens with positive refractive-power, a second lens with negative refractive-power, and a third lens with negative refractive-power located between the first lens and the second lens group, and the first lens, the second lens, and the third lens form a cemented lens; 
 a fourth lens group with positive refractive-power; and 
 a fifth lens group with positive refractive-power, 
 wherein the first lens group, the third lens group, and the fifth lens group are fixed groups, the second lens group and the fourth lens group are movable groups. 
 
     
     
       2. The lens module as claimed in  claim 1 , wherein focal length of the second lens group is f2, focal length of the lens module at a wide-end is fW, focal length of the lens module at a tele-end is fT and the lens module satisfies a following condition expression:
   0.4<| f 2/√{square root over (( fW×fT ))}|<0.6.
 
 
     
     
       3. The lens module as claimed in  claim 1 , wherein focal length of the fourth lens group is f4, focal length of the fifth lens group is f5 and the lens module satisfies a following condition expression: 
       
         
           
             
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       4. The lens module as claimed in  claim 1 , wherein the fourth lens group and the fifth lens group respectively comprise at least one aspheric lens. 
     
     
       5. The lens module as claimed in  claim 1 , wherein the third lens group further comprises a fourth lens with positive refractive-power located between the third lens and the second lens group. 
     
     
       6. The lens module as claimed in  claim 1 , further comprising an aperture stop located between the second lens group and the third lens group. 
     
     
       7. A lens module, having an object-side and an image-side for capturing an object light-beam from the object-side, the lens module disposed on a transmission path of the object light-beam and comprising five lens groups from the object-side to the image-side:
 a first lens group with positive refractive-power; 
 a second lens group with negative refractive-power, wherein focal length of the second lens group is f2, focal length of the lens module at a wide-end is fW, focal length of the lens module at a tele-end is fT and the lens module satisfies a following condition expression:
   0.4<| f 2/√{square root over (( fW×fT ))}|<0.6;
 
 
 a third lens group with positive refractive-power, wherein the third lens group comprises a first lens with positive refractive-power, a second lens with negative refractive-power, and a third lens with negative refractive-power located between the first lens and the second lens group, and the first lens, the second lens, and the third lens form a cemented lens; 
 a fourth lens group with positive refractive-power; and 
 a fifth lens group with positive refractive-power, the fifth lens group comprising at least two lens, 
 wherein the first lens group, the third lens group, and the fifth lens group are fixed groups, the second lens group and the fourth lens group are movable groups and each lens in the third lens group is a spherical lens. 
 
     
     
       8. The lens module as claimed in  claim 7 , wherein focal length of the fourth lens group is f4, focal length of the fifth lens group is f5 and the lens module satisfies a following condition expression: 
       
         
           
             
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       9. The lens module as claimed in  claim 7 , wherein the fourth lens group and the fifth lens group respectively comprise at least one aspheric lens. 
     
     
       10. The lens module as claimed in  claim 7 , further comprising an aperture stop located between the second lens group and the third lens group. 
     
     
       11. An image apparatus, capable of capturing an object light-beam from an object-side and comprising:
 a photosensitive component disposed on a transmission path of the object light-beam and the photosensitive component corresponding to an image-side of the image apparatus; and 
 a lens module, located between the photosensitive component and the object-side and the lens module disposed on a transmission path of the object light-beam and comprising five lens groups from the object-side to the image-side:
 a first lens group with positive refractive-power; 
 a second lens group with negative refractive-power; 
 a third lens group with positive refractive-power, wherein the third lens group comprises a first lens with positive refractive-power, a second lens with negative refractive-power, and a third lens with negative refractive-power located between the first lens and the second lens group, and the first lens, the second lens, and the third lens form a cemented lens; 
 a fourth lens group with positive refractive-power; and 
 a fifth lens group with positive refractive-power, 
 wherein the first lens group, the third lens group, and the fifth lens group are fixed groups, the second lens group and the fourth lens group are removable groups. 
 
 
     
     
       12. The image apparatus as claimed in  claim 11 , further comprising a light-emitting component for emitting an illumination light-beam towards the object-side, wherein the illumination light-beam has a first wavelength range and the illumination light-beam after being reflected by an object at the object-side is converted into the object light-beam. 
     
     
       13. The image apparatus as claimed in  claim 12 , wherein when a luminance at the object-side is less than a predetermined value, the light-emitting component is turned on to emit the illumination light-beam with the first wavelength range towards the object-side, wherein the first wavelength range of the illumination light-beam is the same as a wavelength range of infrared light. 
     
     
       14. The image apparatus as claimed in  claim 12 , further comprising a light-filtering component for blocking the illumination light beam with the first wavelength range, wherein when the luminance at the object-side is greater than the predetermined value, the light-filtering component moves on the transmission path of the object light-beam, when the luminance at the object-side is less than the predetermined value, the light-filtering component leaves from the transmission path of the object light-beam. 
     
     
       15. The image apparatus as claimed in  claim 11 , wherein focal length of the second lens group is f2, focal length of the image apparatus at a wide-end is fW, focal length of the image apparatus at a tele-end is fT and the lens module satisfies a following condition expression:
   0.4<| f 2/√{square root over (( fW×fT ))}|<0.6.
 
 
     
     
       16. The image apparatus as claimed in  claim 11 , wherein focal length of the fourth lens group is f4, focal length of the fifth lens group is f5 and the lens module satisfies a following condition expression: 
       
         
           
             
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                     f 
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                     4 
                   
                   
                     f 
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                     5 
                   
                 
                 ) 
               
               < 
               
                 0.65 
                 . 
               
             
           
         
       
     
     
       17. The image apparatus as claimed in  claim 11 , wherein the fourth lens group and the fifth lens group respectively comprise at least one aspheric lens. 
     
     
       18. The image apparatus as claimed in  claim 11 , wherein the third lens group further comprises a fourth lens with positive refractive-power located between the third lens and the second lens group. 
     
     
       19. The image apparatus as claimed in  claim 11 , further comprising an aperture stop located between the second lens group and the third lens group.